Furnace.



UNITED `STATES PATENT FRANK n. HILL, oF KEELEB., cALIFoItNIA, AssIGNoR To WILFRED W. wATTEEsoN,"oF

` BISHOP, CALIFORNIA. .f

FURNACE.

To all 'whom t may concern: v n Be it known that I, FRANK R. HILL, c1t1- zen of the United States, residing at Keeler',

in the county of Inyo, State of California,

have invented new and useful Inrprovements in Furnaces, of which the following is a specification.

This invention relates generally to furnaces which may be used for smelting, reducing, melting or fusing ores and other minerals or other substances; and there are certain comprehensive objects and accomplishments of the invention which apply generally to the .lse of the invention for any such purpose, or any similar purpose, all as will be hereinafter set forth. Besides these general objects of the invention, there are certain other more specific objects directed particularly to the use of the furnace for the purpose of melting or fusing such minerals as sodium carbonate and the like. I have developed the particular form of furnace herein described, and illustrated in the accompanving drawings, for the purpose of operating u on sodium carbonate; but it` will be readlly and clearly .understood that my invention is not limited to such usevbut may, with any necessary modifications or changes, be made suitable for other various uses. Accordingly, the following specific description of the furnace as applied to s0- dium carbonate etc. will not be taken as a limitation upon my invention.

In devices which have heretofore been used for treating such a mineral as sodium bicarbonate, to convert it into sodium carbonate, difficulty has been experienced in a number of directions. In the first place it is extremely diflicult to obtain materials which will withstand the required heat in the presence of the carbonate Furnaces of this character have been of necessity'renewed at regular periods at a very large expense. It is one of the objects of this invention to provide a furnace in which the structure and arrangement is such that the furnace walls are protected. Now this object of' the invention, although it is one which particularly. and specifically bears upon the problem of furnacing sodium b1- carbonate, also is a general object as applied to the use of the furnace for any other purpose. In my furnace the walls are protected from the heat, and also from any chemlcal action or deterioration which might otherwise go on if the heated materials are specification of Letters' Patent. i Patented Nov. 5,1918.

Application med Maren 5, 191s. serial 1ra-220,440, i

brought into intimate contact with ed walls.

It 1s also a general object of the mventlon to provide a furnace structure 111 which there is a very large surface of the materiali, exposed to dlrect heat action; and'in which the heated, fused, or melted material f (or the material in its finally treated state);l lis moved out of the zone of heat and lout of the furnace immediately after it has`fbeen.y subjected to the highest heat and immedi" ately upon the completion of the yoperation desired to be effected. These two objects'are general objects of the invention applicable to any use to which the furnace maybe put; .v but the later named object is also a particu-i lar .and specific oneas applied to the furnacing of sodium blcarbonate.` In furnacing sodium bicarbonate to change it into sodium carbonate, it is found that if thesub-j., stances are subjected too long to high heat action, or are subjected to an unnecessarily high temperature, the resulting product- 'will contain an objectionably high percentageof caustic soda. `It 1s a particularjobject of u this invention to provide a furnace in which the formationA of caustic is preventedfor greatly minimized. n i f l It is a further general object of the invention to provide a furnace of large treatf, v ing capacity and of great fuel economy; to

provide a type of furnace in which continuous operation may be effected, in'contradistinction to the previous intermittent or batch operation; and it is also an object'to reduceV the actual cpst of the furnace and todo away as far as possible with the useof'a large amount ofexpensive fire-proof material, and to materially increase the life-f of the furnace. v In fact, I may here say thatd, although furnaces which havev heretoforef-` been used for the purposes herein described, have been necessarily renewed every few months, my furnace has a moreror less indefinitely long life.

In the accompanying drawings I illus-d'5 trate a specific preferred form `of, furnace adapted particularly for operations' upon the materials herein specified; and in these drawings- Figure 1 is a vertical central section'of I In the drawings vI show a furnace struc@l i' ture having a circular outer wall 10 supported upon any suitable sub-structure 11; and the whole furnace and sub-st-ructlu'e is preferably composed of brick or other suit.- ablc materia-l. The furnace is roofed with an arch 12 and has a floor 13 which prefcrablv drops on all sides toward the center of tlic furnace. The various sizes of the parts arc shown in approximately correct proportions of the drawings. In a. furnace which is approximately thirteen feet internal diameter. I have about a four-inch drop on the floor from the outer edge to the center. The inner facing of the furnace may be made of heat resist-ant material, such as ordinary fire brick; but the body of the furnace-walls` foundation, etc., are made of ordinaly red brick, or of any other suitable material. In the center of the furnace floor there is an outlet well 15 and around this well I preferably place a ledge 1G which is for the purpose of prevent-ing any solid material from rolling into the well 15. This circular ledge 16 may have notches or c ut's 17 therethrough for the purpose of allowinfr ready and immediate outflow of the melted or fused material from the space immediately surrounding the ledge. However, this protective ledge may or may not be used, as best suits the particular purpose to which the furnace is put.

A draft flue 18 leads off from the lower, part of the well and through this draft flue the heated air and products of combustion are drawn olf. In the process of treating sodium bicarbonate I may take these products of combustion to apparatus in which the bicarbonate is dried previous to putting the material into this furnace; but the rescnt invention is not concerned particu arly with such procedures, and so I illustrate a draft stack at 18a which will typify any suitable means for drawing 0E the products of combustion and for causing the operations hereinafter described. However, I may here explain that it is one ofthe specific advantages of my invention that the draft flue is low down (due to the draft coming out of the bottom of the furnace), and that this position of the draft flue enables me to conveniently pass the products of combustion through other apparatus (as heating or drying apparatus) before finally passing them to the atmosphere through a stac t.

A tap hole 19 leads out from the Well 15; and through this tap hole the melted 0r fused material is drawn olf. In using the furnace for melting ores and the like, the melted metal may be handled in any desired manner when it is Withdrawn from the tap hole; but in the particular and specific use which I herein describe, I make arrangements for atomjzing the stream of melted carbonate which issues from the tap hole 19.

For this purpose the tap 19 discharges into a tunnel 20 and the melted material drops down immediately in front. of an air blast pipe 21, through which an air blast is maintained at a suitable pressure, say S or 10 ounces per square inch or more. The air blast through this pipe blows the stream of material into line particles so that the ma terial is blown in finely divided state out through the tunnel 20 and thence into any suitable receiver which is indicated at 22 in Fig. 4. An observation tunnel 9 is provided for the purpose of observing the action of the air blast on the stream of molten material.

The material `to be treated is fed into the furnace through its roof and around its Wall so that the material forms an annular pile against the circular walll of the furnace, with an inverted conical open space Within the annular pile of material, and the material presenting an inner inverted conical surface to the action of flame and heat within the furnace. The particular material of which I herein speak, bicarbonate of sodium, piles at about the angle illustrated in the drawings. In the drawings the material is indicated at It It will be seen that the circular wall of the furnace is amply protected by the thickness of material in front of it. The furnace is so designed that the foot of the annular pile of material will stand about four or six inches from the cir cular ledge 16; or, in any case preferably just far enough from the circular ledge to prevent any solid material which might roll down the face of the pile going over into the well 15. For the purpose of feeding the material I may use any suitable means; but I preferably use means which Will feed the material evenly around the periphery of the furnace, and Will also feed it continuously; so as continuously to keep an even annular pile of material in the furnace. I may provide a plurality of feeding tubes 25 which are f ed at their upper ends from an annular trough 26 by the action of an annular feeder or spreader Which rotates around. 1n the trough, the material being delivered into the trough in any suitable manner, as through a chute 28. The feeder may be rotated in any suitable manner. It may comprise two annular members 27 lying in the trough 26 against its inner and outer Walls, joined by cross members 27a which act as Scrapers to move the material along the trough, filling any of the feeding tubes 25 which are not full of material. However, any suitable means may be used for evenly feeding material to the several feed tubes 25; or, in general, I may use any means for evenly and continuously feeding the material into the furnace around its upper edge, or for feeding the material into an annular pile surrounding the burner.

The burner, which uses fuel oil, is shown at 30, and projects down into the furnace centrally through the arch 12. The burner may be of any suitable type and preferably one that will spread the fuel, and the. flame, out more or less horizontally and circularly around the head 30 of the burner. Such a burner may be operated with fuel oil and with air under pressure. Air for combustion in the furnace is admitted through an air pipe shown at 31. This air pipe adm-its air to the. upper center of the furnace. The action of the burner throwing the fuel outwardly horizontally, has a tendency to cause the air to flow in the direction indicated by the arrows; causing the cool incoming air to spread out in the furnace under the arch and then causing the air to be drawn down into the combustion which then takes place. in a more o1' less Well defined inverted cone over the inverted conical exposed surface of the material. The furnace arch is ell'ectually protected from deterioration by heat by this direction of flow of the incoming cool air. Air may be supplied to pipe 31 under a sui-table pressure; in the present instance about two ounces to the square inc-h. The flame and products of combustion are directed and drawn by the draft into the well 15, 'and the products of combustion then pass out through the flue 18. I have hereinbefore explained that the draft in flue 18 may be created by any 'desired means. The burner is so regulated that, in the present instance, the hottest part 0f the flame is approximately at or near the upper open end of the well. The flame plays downwardly upon the sloping conical surface of the material and the material is fused and melted, and the melted material runs down -the sloping surface and immediately passes into the well. The highest temperature employed is of course regulated to suit the material being opera-ted upon. In the present instance this temperature may be approximately 1200 to 1100 degrees F. Immediately the material has been subjected to the highest temperature, it passes directly out of the zone of highest temperature and passes quickly out of the furnace by a very short route.

From the foregoing description the application of my invention to the treatment of sodium carbonates, and the advantages accruing therefrom, are to be readily understood. Speaking now more generally of the advantageous features of my furnace, without restriction as to its use, it will be seen that there are various improvements of some importance. The feature of utilizing an annular pile of material exposing its inner surface to the action of flame is a feature which leads to many good results. In the first lace, a comparatively large area of materiaFis exposed eiii'ciently to a sin le flame. The arrangement is such that all o the portions of the llame come into very close proximity, or into actual contact with the surface of the material; and that the whole of the exposed surface of the material may be very readily acted upon by the flame. Consequently, a great increase in etiiciency is to be expected; and I find by actual practice that this expectation is realized in so far that I have been already lable to obtain from a furnace of this character about twice the output as from an old style furnace of the same size; and to obtain this doubled output with the use of approximately one-half the fuel necessary in the older kind of furnace.

Another generally advantageous feature of the furnace lies in the fact that a free and unchoked surface of the material is presented at. all times to the action of the. flame.

This is a feature which is not, only particuv larly desirable in the specific use of the furnace herein set forth, but is also partielllarly desirable in the smelting or melting of ores and metals with the use of petroleum or similar fuel. One of the dilieulties so far encountered in the smelting, etc. of ores and metals with hydrocarbonaeeou's fuels has been the clogging ofthe mass of material after a certain amount of heat treatment, prevent further access of the heatino flame to the material, and thus stopping fiirther action. In my furnace this action cannot take place; for as fast as the material is fused andmelted, it passes directly out of the furnace; and new material is continuously exposed on the exposed inner face of the annular pile.

Aside from the great increase in eiiicieno of this furnace, the decreased initial cost an the decreased cost of repair or replacement is a very material and important thing in the industries to which the furnace appertains. It is readily to be seen without further detailed explanation, that my furnace may be built With cheaper materials, or with a less quantity of high priced heat resisting materials; and is consequently much more inexpensive to begin with. Furthermore this furnace does not need periodic renewal, which is an item of very large expense in the older kinds of furnaces. In my imlproved furnace, although I have explained that the inner facing of the furnace may be of firebrick, even this m-ay not in some cases be necessary. -In the older kind of furnaces the inner facing has been constructed of magnesite, which is an expensive material and expensive of installation. In the present case I preferably make the annular ring 16 of magnesite; and under some circumstances it may be necessary to renew this ring 16; but such renewal is easily, quickly and inexpensively made.

The continuous nature 'of operation is also an advantage, `not only because it leads to increased output but because it keeps the furnace continuou-sly heated. No loss occurs from the alternate cooling and reheating of the furnace, and the usual furnace deterioration due to the alternate heating and cooling is done away with.

I have now proceeded to describe a preferred form of my invention in some particularity and detail; but it will be fully understood that I do not thereby limit my invention to the specific details herein set forth; but rather do I believe my invention to be broad in its nature and scope, and I accordingly reserve to myself any changes and modifications such as may suggest themselves to those skilled in the art or such as may fall within the scope of the following claims. A

Having described a preferred form, of my invention, I claim:

1. A furnace embodying a structure having a chamber with an outlet in its floor, means to feed material into the furnace to stand in an annular pile with its foot around the outlet, and means to apply heat to the inner sloping surface of the annular pile.

2. A furnace, embodying a structure having a substantially circular chamber with a substantially central outlet in its floor, means to feed material evenly and continuously around its upper part into the furnace chamber to stand in an annular pile around the wall of the furnace chamber, the proportions of the chamber being such that the pile standing against the wall has its inner surface on all sides sloping toward and has its foot around the lower outlet, and means to apply heat to the inner surface of the annular pile.

3. A furnace embodying a structure having a chamber with an outlet in its floor, means to feed material into the furnace to stand in an annular pile with its foot around the outlet, and means to apply heat to the inner sloping surface of the annular pile, said means embodying a central liquid fuel burner projecting a flame outwardly toward the inner surface of the pile somewhat above its fcot.

4. A furnace embodying a structure having a chamber with an outlet in its floor, means to feed material into the furnace to stand in an annular pile with its foot around the outlet, combustion means to apply heat to the inner surface of the annular pile, and a draft ue connected to the outlet to draw the heat downwardly and the products of combustion out of the chamber through the outlet.

5. A furnace embodying a structure having a chamber with an outlet in its floor, means to feed material into the furnace to Lasagne stand in an annular pile with its foot around the outlet, combustion means to apply heat to the inner surface of the annular pile, said means embodying a central liquid fuel burner projecting a flame outwardly toward the inner surface of the pile somewhat above its foot, and a draft flue connected to the outlet to draw the heat downwardly and the products of combustion out of the chamber through the outlet.

6. A furnace, embodying a structure having a substantially circular chamber with a substantially central outlet in its floor, the floor sloping from all sides to the outlet, means to introduce material to the upper part of the chamber around its outer wall so as to form an annular pile of material in the chamber banked against the outer wall with its foot around the central outlet, and means to apply heat to the inner surface of the annular pile of material.

7. A furnace embodying a structure having a substantially circular chamber with a substantially central outlet through its door, means to introduce material to the upper part of the chamber around its outer wall so as to form an annular pile of material in the chamber banked against the outer wall with its foot around the central outlet, a raised rim around the outlet, and means to applying heat to the inner surface of the annular pile of material.

8. A furnace, embodying a structure having a chamber with an outlet in its floor, means to feed material into the furnace to stand in an annular pile around the outlet, combustion means to heat the inner exposed surface of the pile, means to admit air to the upper part of the furnace over the combustion means, and draft means connected to the outlet.

9. A furnace, embodying a structure having a chamber with an outlet in its floor, means to feed material into the furnace chamber to stand in an annular pile in the furnace chamber around the outlet, means to apply heat to the inner surface of the annular pile, said means embodying a central liquid fuel burner projecting a llame outwardly toward the inner'surface of the pile, a draft Hue connected to the outlet to draw the heat downwardly and the products of combustion `out of the furnace chamber, and means to admit air to the chamber above the liquid fuel burner.

In witness that I claim the foregoing I have hereunto subscribed my name this 20th day of February, 1918.

FRANK R. HILL.

Witness:

A. T. SMITH. 

